AVL steady flow test was carried out on 170 series diesel double-intake port, and the AVL flow coefficient and swirl ration under different air valve lift were obtained. With the same boundary conditions and evaluation methods, CFD software Fire was applied to simulate the steady flow in intake port. The comparison results show that the flow coefficient and swirl ratio from numerical simulation are consistent with those from testing, and the accuracy of simulation is acceptable. In addition, according to the proportional relation between swirl ratio and valve lift, the machined eccentric chamfer on valve seat of tangential port has a profound impact on swirl generation, especially in condition of small valve lift, which may result in bigger swirl ratio.